DESCRIPTION:(provided by applicant) In the past several years, songbirds have increasingly become a useful model system for studying the functional role of the basal ganglia pathway loop in complex behaviors such as learned vocal communication. In young birds, the vocal part of the basal ganglia pathway is required for song learning. In adults who have learned their songs, it is not necessary for production of learned vocalizations, but shows dramatic changes in gene activation depending upon the social context in which vocalizing occurs. This context-dependent vocal gene activation lead to a number of intriguing testable hypotheses of the basal ganglia's functional role in adult vocal communication. These ranged from 1) regulating gene expression and activity of the vocal motor pathway to 2) generating on-line complexity of the singer's vocalizations. The goals of the experiments in this proposal are to test these hypotheses and, in doing so, to determine the basic function of the vocal basal ganglia loop in learned vocal communication. Since the loop is built within a circuit that is conserved in the vertebrate brain, it is believed that the underlying mechanisms discovered will generally apply to complex social behaviors such as learned vocal communication in humans. However, since vocal learning is a very rare trait, as it is only found in 3 groups of mammals (humans, dolphins, and bats) and 3 groups of birds (songbirds, hummingbirds and parrots), with songbirds being the most studied animal model, the results of this proposal are expected to generate unique insight into higher order brain function, and insight into diseases that affect speech, language, and cognitive processes.